<template>
   <view>
      <view class="scroll-view-container">
        <!-- 左侧的滚动视图区域 -->
        <scroll-view class="left-scroll-view" scroll-y :style="{height: wh + 'px'}">
          <block v-for="(item, index) in cateList" :key="indx">
            <view :class="['left-scroll-view-item',index === active ? 'active' : '']" @click="changeClick(index)">{{ item.cat_name }}</view>
          </block>
        </scroll-view>
        <!-- 右侧的滚动视图区域 -->
        <scroll-view class="right-scroll-view" scroll-y :style="{height: wh + 'px'}" :scroll-top="scrollTop">
          <view class="cate-lv2" v-for="(item2, i2) in cateLevel2" :key="i2">
           <view class="cate-lv2-title">/ {{item2.cat_name}} /</view>
            <!-- 动态渲染三级分类的列表数据 -->
            <view class="cate-lv3-list">
              <!-- 三级分类 Item 项 -->
              <view class="cate-lv3-item" v-for="(item3, i3) in item2.children" :key="i3" @click="goGoodList(item3)">
                <!-- 图片 -->
                <image :src="item3.cat_icon"></image>
                <!-- 文本 -->
                <text>{{item3.cat_name}}</text>
              </view>
            </view>
          </view>
        </scroll-view>
      </view>
    </view>
</template>

<script>
  export default {
    data() {
      return {
        wh: 0,
        // 分类数据列表
        cateList: [],
        active: 0,
        cateLevel2: [],
        scrollTop: 0
      };
    },
    onLoad() {
      // 获取当前系统的信息
      const sysInfo = uni.getSystemInfoSync()
      // 为 wh 窗口可用高度动态赋值
      this.wh = sysInfo.windowHeight
      // 调用获取分类列表数据的方法
      this.getCateList()
    },
    methods:{
      async getCateList() {
        // 发起请求
        const { data: res } = await 
        uni.$http.get('/api/public/v1/categories')
        // 判断是否获取失败
        if (res.meta.status !== 200) return uni.$showMsg()
        // 转存数据
        this.cateList = res.message
        this.cateLevel2 = this.cateList[0].children
      },
      changeClick(index){
        this.active = index
        this.cateLevel2 = this.cateList[index].children
        this.scrollTop = this.scrollTop === 0 ? 1 : 0
      },
      goGoodList(item) {
        uni.navigateTo({
          url: '/subpkg/goods_list/goods_list?cid=' + item.cat_id
        })
      }
    }
  }
</script>

<style lang="scss">
.scroll-view-container {
  display: flex;
  .left-scroll-view {
    width: 120px;
    .left-scroll-view-item {
      line-height: 60px;
      background-color: #f7f7f7;
      text-align: center;
      font-size: 12px;
      // 激活项的样式
      &.active {
        background-color: #ffffff;
        position: relative;
        // 渲染激活项左侧的红色指示边线
        &::before {
          content: ' ';
          display: block;
          width: 3px;
          height: 30px;
          background-color: #c00000;
          position: absolute;
          left: 0;
          top: 50%;
          transform: translateY(-50%);
        }
      }
    }
  }
  .cate-lv2-title {
    font-size: 12px;
    font-weight: bold;
    text-align: center;
    padding: 15px 0;
  }
  .cate-lv3-list {
    display: flex;
    flex-wrap: wrap;
    .cate-lv3-item {
      width: 33.33%;
      margin-bottom: 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      image {
        width: 60px;
        height: 60px;
      }
    }
  }
 }
</style>
